1. Field of the Invention
The present invention relates to a storage system for storing articles in warehouses, etc. Particularly, the present invention relates to a storage system in which storage articles are taken in and out of the storage system according to indications output from hand-held terminals.
2. Description of the Related Art
In conventional management systems for stored articles in warehouses or stock goods in stores, operators confirm the existence of articles arranged on racks according to forms on which articles to be taken in and out are indicated, then the operators take the articles to the corresponding racks or take them from the racks. The articles to be taken in and out are recorded on the forms. However, when these operations are carried out by people, there occurs a problem that articles are not correctly taken in and out because of human errors. Particularly, this problem becomes serious when many kinds of articles are stored. Further, in some systems, storage locations of articles are flexibly changed in order to effectively use storage spaces. In these systems, storage space from which all articles are taken out (i.e., removed) are used to store other articles. Therefore, because the storage locations of the articles frequently change, operators cannot easily look for the locations corresponding to the articles to be taken in and out. This increases the operation time. For example, in the warehouse used to store seasonal goods, stored articles change according to seasons; therefore, the storage locations of the articles must be changed according to these changes of the stored articles in order to effectively use the storage spaces.
Further, some kinds of articles, such as clothes, require special knowledge to discriminate. Therefore, when these articles are stored in the warehouse, it is not easy to correctly check the articles to be taken in and out. This also causes errors.
Computers can be used to manage the stored articles. The computer outputs a list which indicates articles to be taken in and out. In order to correctly and effectively take in and out articles, the articles themselves or the locations of the articles employ information indication means such as bar codes which indicate information concerning the stored articles in forms that can be converted into electrical signals; then, the articles are taken in and out after reading the information indication means by using bar code scanners, etc., provided at hand-held terminals. The communications between the host computer and the hand-held terminals are carried out by using radio communication means or by connecting the hand-held terminals to the host computer.
When the communications are carried out by using radio communication means, for example, a bar code of the article is read by the hand-held terminal, then, the bar code data read by the hand-held terminal is transmitted to the host computer. The host computer determines whether the received bar code data is in the list of articles to be taken in and out, then, the result is transmitted to the hand-held terminal. The hand-held terminal displays this result on its display device, and the operators carry out the operations by referring to this result. In this way, errors in the operations are reduced because the article to be taken in and out can be checked.
In the above operations, the checking operations used to take in articles are similar to those used to take out articles, therefore, the examples to take out articles will be explained in the following. The operations to take out articles from the warehouse and so forth are called "picking". Therefore, in the following, this word will be used.
However, in the above operations, the communication is carried out when the bar code is read by the hand-held terminal; therefore, there occur problems that the operations become complicated and the operation times become long.
When the hand-held terminals are connected to the host computer in order to communicate with the host computer, all the information necessary to carry out the picking operation is transmitted at one time. The hand-held terminal stores the information, then, when the bar code of the article is read, the hand-held terminal determines whether the received bar code data is in the list of articles to be picked and displays this result on its display apparatus. In this method, it is not necessary to communicate with the host computer when the bar code is read by the hand-held terminal. This method can be applied to the system using the radio communication means.
The hand-held terminals having radio communication means are very expensive; therefore, there occurs a problem that the storage system having these hand-held terminals becomes expensive. Further, because environments in which the radio communications can be freely carried out are limited, there exist some cases in which these systems cannot be used.
When the communications are carried out by connecting the hand-held terminals to the host computer, the hand-held terminals must be transferred to the location of the host computer whenever the communications between them must be carried out. Particularly, when the host computer is located apart from the storage system, the time necessary for round trips between them becomes long, then, the operation time becomes long.
Further, as described above, in some systems in which storage locations of articles are flexibly changed in order to effectively use storage spaces, the problem that the operation time is long cannot be resolved by using the bar codes which are attached to articles or locations of articles.